U.S. patent number 5,688,192 [Application Number 08/482,518] was granted by the patent office on 1997-11-18 for solid construction golf ball incorporating compressible materials.
This patent grant is currently assigned to Acushnet Company. Invention is credited to Steven Aoyama.
United States Patent |
5,688,192 |
Aoyama |
November 18, 1997 |
**Please see images for:
( Certificate of Correction ) ** |
Solid construction golf ball incorporating compressible
materials
Abstract
The subject invention relates to a golf ball having the
beneficial characteristics of both a wound and solid construction
ball. The invention is directed to a non-wound golf ball
incorporating a compressible material, such as a gas, as part of
its core. The compressible material can be dispersed throughout the
entire core or only in a part of the core. The compressible
material or gas can be incorporated into the core by including or
dispersing microspheres having a flexible shell containing the
compressible material or gas. The golf balls of this invention
combine the feel and playing characteristics of a wound
construction ball with the shelf-life, manufacturing simplicity and
durability of solid construction golf balls.
Inventors: |
Aoyama; Steven (Marion,
MA) |
Assignee: |
Acushnet Company (Fairhaven,
MA)
|
Family
ID: |
23916390 |
Appl.
No.: |
08/482,518 |
Filed: |
June 7, 1995 |
Current U.S.
Class: |
473/374; 473/369;
473/370; 473/377 |
Current CPC
Class: |
A63B
37/0003 (20130101); A63B 37/0035 (20130101); A63B
37/0045 (20130101); A63B 37/0056 (20130101); A63B
37/0064 (20130101); A63B 37/0074 (20130101); A63B
37/0075 (20130101); A63B 37/06 (20130101); A63B
2039/006 (20130101) |
Current International
Class: |
A63B
37/00 (20060101); A63B 37/06 (20060101); A63B
39/00 (20060101); A63B 37/02 (20060101); A63B
037/06 () |
Field of
Search: |
;273/230,231,6R
;473/371,377,372,373,374,375,376,352,355,256 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Marlo; George J.
Attorney, Agent or Firm: Pennie & Edmonds LLP
Claims
I claim:
1. A finished regulation long range, solid construction,
multi-piece golf ball comprising a discrete cover and a core, said
core comprising an inner and an outer portion, said inner portion
having a plurality of gas containing compressible cells dispersed
therein.
2. The golf ball of claim 1 wherein said cells comprise about 5% to
50% by volume of the entire core.
3. The golf ball of claim 2 wherein said cells comprise about 10%
to 15% by volume of the entire core.
4. The golf ball of claim 1 wherein said cells are dispersed
throughout substantially the entire core.
5. The golf ball of claim 4 wherein said cells comprise a plurality
of microspheres having a flexible outer surface.
6. The golf ball of claim 5 wherein said surface is formed from a
polymer.
7. The golf ball of claim 6 wherein said polymer is an
acrylonitrile copolymer.
8. The golf ball of claim 5 wherein each said microsphere has a
diameter of about .ltoreq.10% of that of the entire core.
9. A finished regulation long range, solid construction,
multi-piece golf ball comprising a discrete cover and layered core,
said core comprising an outer layer and an inner layer, said inner
layer having a plurality of gas containing compressible cells
dispersed therein.
10. The golf ball of claim 9 wherein said cells comprise a
plurality of microspheres having a flexible outer surface.
11. The golf ball of claim 9 wherein said cells are dispersed in a
layer within said core inner layer having a thickness of about
0.05-0.80 inches.
12. The golf ball of claim 9 wherein said cells are dispersed in a
layer within said core inner layer having a thickness of about
0.10-0.25 inches.
Description
BACKGROUND OF THE INVENTION
Present day golf balls can be classified under one of two
categories: solid balls and wound balls. The first category of
solid balls includes unitary or one-piece golf balls as well as
multi-piece balls. One-piece golf balls, seldomly used as playing
balls, are typically made from a solid piece of polybutadiene
rubber, with dimples molded into its surface. Although inexpensive
and durable, these unitary balls are generally limited to use as
practice balls because they do not give the desired distance when
hit. In contrast, multi-piece solid balls usually consist of a core
of hard, polymeric materials enclosed in a distinct, cut-proof
cover made of DuPont's SURLYN, an ionomer resin. Because of its
durability and low spin, which produces greater distance and
reduced hooking and slicing, this type of ball is the most popular
among ordinary players.
Wound golf balls are manufactured by wrapping elastic windings
under high tension around a solid rubber or liquid filled center. A
cover, usually SURLYN or balata is molded over the windings to form
the ball. This winding process naturally incorporates a certain
amount of trapped air within the layer of windings. The air trapped
within a wound construction ball provides certain characteristics
which are considered by many golfers to be desirable. It creates a
soft feel at impact due to its compressible nature and high
resiliency due to its high efficiency (low damping) as a spring.
For skilled golfers, these wound balls typically provide a higher
spin rate and offer more control over the ball's flight than solid
balls.
Unfortunately, the wound construction is also more difficult and
expensive to manufacture than solid construction golf balls. Also,
wound golf balls have comparatively shorter shelf life and lower
resistance to certain types of damage than solid balls.
Various attempts have been made to mimic these wound construction
benefits using solid construction manufacturing techniques.
However, these balls generally have used softer core materials,
softer cover materials, layers of soft materials combined with
conventional materials or combinations thereof. Examples of such
balls include the Titleist HP2, Pinnacle Performance, Ultra
Competition, Ultra Tour Balata, Maxfli HT Hi Spin, Precept EV Extra
Spin, Altus Newing, Top-Flite Tour Z-Balata, Top-Flite Tour and
Kasco's "Dual Core" balls. Likewise U.S. Pat. No. 4,650,193 to
Molitor also discloses a golf ball made from relatively "soft"
materials. While these solid constructions sometimes produce
improved feel or playing characteristics which simulate those of
wound balls, they fail to completely capture the same desired
characteristics. In addition, the soft materials often produce
compromised resilience or durability or both.
This invention takes a different approach. Instead of using soft
but incompressible materials, it employs compressible materials
such as gases in the core of a solid construction golf ball. This
approach provides a much better simulation of the effects of the
trapped air in a wound construction golf ball while using a
manufacturing process similar to that for solid golf balls. The
result is a ball having the soft feel and high resilience of wound
construction balls combined with the manufacturing simplicity,
shelf life and durability of solid construction balls.
Although prior art golf balls have employed such a gaseous
component, these balls have been typically special purpose balls or
balls where only the covers incorporate such a material as
disclosed in U.S. Pat. Nos. 5,150,906 and 4,274,637 to Molitor et
al. and U.S. Pat. No. 4,431,193 to Nesbitt. Representative of
special purpose balls are short-distance balls such as those
disclosed in U.S. Pat. No. 4,836,552 to Puckett et al., floater
balls such as those described in U.S. Pat. No. 4,085,937 to Schenk
and "Nerf" type toy and practice balls. These balls incorporate gas
in the ball materials for the purposes of reducing the ball's
weight and/or its potential for causing damage to a struck object.
They do not feel or perform in any way like a normal wound or solid
construction golf ball.
SUMMARY OF THE INVENTION
This invention relates to multi-piece golf balls and their method
of manufacture. In particular, this invention is directed towards
golf balls comprising a core of a material incorporating a
compressible gaseous material or cellular material, and a spherical
cover or shell of polymeric material.
In addition this invention provides a solid construction golf ball
having the beneficial characteristics of both wound and solid
construction type balls. The golf balls of this invention combine
the feel and playing characteristics of a wound construction with
the shelf life and durability of a solid construction golf
ball.
Furthermore, the golf balls of this invention will have advantages
over both conventional solid as well as wound construction balls in
cold weather. Under such conditions, solid construction balls
develop a very hard feel due to the stiffening of the materials.
They do, however, retain most of their resilience so they do not
lose much distance. On the other hand, wound construction balls
retain much of their soft feel (because the entrapped air does not
stiffen significantly), but they lose distance due to a loss of
resilience in the high tension windings. A ball made according to
this invention will retain softness like a wound ball, and retain
resilience like a solid construction ball.
Another objective of this invention to provide a golf ball having
the desired characteristics of a wound construction ball and the
manufacturing simplicity and cost-savings of a solid construction
ball.
This invention is further directed towards the manufacture of a
solid construction golf ball possessing the performance
characteristics of a wound ball and benefits of solid construction
balls.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a golf ball of this invention
where the solid core is made of a material incorporating a
compressible gaseous material.
FIG. 2 is a cross-sectional view of a golf ball of this invention
where the outer layer of the core is made of a cellular material or
a material incorporating a compressible gaseous material.
A DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The key to this invention is that compressible materials are
incorporated into the construction of the golf ball. "Compressible
materials" are materials whose density is strongly affected by
pressure or temperature. Gases would generally be considered to be
compressible materials while liquids and solids would not be.
As defined in this invention the word "core" refers to unitary
cores as well as multi-layered cores. The compressible materials of
this invention can be incorporated into the entire core or into at
least one layer of the core. Preferably the compressible gaseous
material is incorporated into the outer layer of a multi-layered
core so that the golf ball behaves and plays more like a wound
ball. The thickness of the layer containing the Compressible
material preferably ranges from about 0.05 inches to 0.80 inches,
which is generally the diameter of the entire core. More
preferably, the thickness of such layer ranges from about 0.10 to
0.25 inches.
The figures exemplify two embodiments of this invention. These
figures are provided to further the understanding of this invention
and are not to be construed as limiting the claims in any manner.
FIG. 1 illustrates a golf ball 1 which includes the compressible
material in the entire core 2. To complete the ball, a cover 3 is
molded over the core 2. In FIG. 2, the ball 1 comprises a multiple
layered core 2 comprising an inner core layer 4 and an outer core
layer 5. The compressible material is incorporated into the outer
core layer 5.
Suitable core materials into which the compressible gaseous
material can be incorporated include solids and liquids. In
general, the core material will essentially be incompressible.
Among these materials is polybutadiene, a polymer which is
presently used to make cores for nearly all commercial golf balls.
Also, various thermoplastic materials such as DuPont's SURLYN, an
ionomer resin, DuPont's Hytrel, or B.F. Goodrich's Estane, or
blends thereof, could be used. Furthermore, materials which are not
normally resilient enough for use in golf ball cores but may be
satisfactory when the compressible gaseous material is incorporated
into it may be used. One such example is polyurethane.
The proportions of compressible gaseous material to core material
that are suitable will depend upon the core materials used as well
as the performance characteristic or effects that are desired of
the golf ball. In general, a range of about 5% to 50% compressible
material by volume of the core layer containing the compressible
material is suitable. For outer core layers which have thicknesses
equivalent to that of the winding layer in wound balls, 10-15%
compressible material by volume of the outer core layer is
preferred. However, for thinner layers or layers made of stiffer
materials, a higher proportion of compressible material to core
material is recommended. Preferably, the compressible material is
distributed uniformly in the core layer or entire core.
The gaseous materials can be incorporated into the core polymer in
a number of ways. The core polymeric materials can be "foamed" by
various techniques which include, but are not limited to the use of
blowing agents, gas injection, mechanical aeration and
two-component reactive systems. U.S. Pat. No. 4,274,637 to Molitor
describes the use of blowing agents and gas injection to foam
polymeric materials. Blowing agents foam the core polymeric
materials by decomposing to form gases which are absorbed by the
materials. The gas then expands to form the foamed core materials
or cellular core material. Foaming by gas injection can be achieved
by injecting a gas under pressure such as nitrogen, air, carbon
dioxide, etc. into the material. When the gas expands, the material
is foamed.
In addition, the gas can be added to the core material by the
inclusion of gases encapsulated in microspheres. This addition can
be done by mixing gas-filled microspheres into the polymer
composition. However, the encapsulating envelope of such gas must
be of a material flexible enough to permit compression of the gas
inside during impact. Such encapsulating materials include
polymeric microspheres, such as acrylonitrile copolymer
microspheres, as well as expandable microspheres. However, glass
microspheres would not be appropriate for this invention because of
their rigidity.
Regardless of the materials from which they are made appropriate
microspheres must be of a size such that they be small enough to
act like a continuous medium when incorporated into the core
material. Typically a microsphere diameter on the order of at most
10% of the thickness of the core layer incorporating the
compressible material is suitable.
Moreover, various crosslinkers and fillers can be added to the core
materials along with the gaseous material. Suitable cross-linking
agents include metallic salts of an unsaturated carboxylic acid.
These salts are generally zinc diacrylate or zinc dimethacrylate.
Of these two crosslinkers, zinc diacrylate has been found to
produce golf balls with greater initial velocity than zinc
dimethacrylate.
Suitable fillers that can be used in this invention include free
radical initiators used to promote crosslinking of the salt and the
polybutadiene. The free radical initiator is suitably a peroxide
compound such as dicumyl peroxide, 1,1-di (T-butylperoxy)
3,3,5-trimethyl cyclohexane, a--a bis (T-butylperoxy)
diisopropylbenzene, 2,5-dimethyl-2,5 di (T-butylperoxy) hexane, or
di-T-butyl peroxide, and mixtures thereof. Also other substantially
inert fillers such as zinc oxide, barium sulfate and limestone as
well as additives can be added to the mixture. The maximum amount
of fillers utilized in a composition is governed by the specific
gravity of the fillers as well as the maximum weight requirement
established by the U.S.G.A. Appropriate fillers generally used
range in specific gravity from 2.0-5.6.
There are generally two basic techniques used in the manufacture of
golf balls: Compression molding and injection molding. Both these
techniques are well-known in the art. For an inventive ball having
the compressible material dispersed throughout the core, the gas is
incorporated by adding the microspheres or by some other foaming
technique into polybutadiene or some other suitable core material.
After the addition of the compressible materials, the core material
composition is then extruded into preforms suitable for molding.
The preforms are then compression molded into spherical cores. The
cover, typically of a thermoplastic material, is then either
injection molded directly around the core or compression molded
using pre-formed hemispheres of cover material placed around the
core. Such cover materials, such as SURLYN or balata rubber, are
known in the art.
For an inventive ball where the compressible material is
incorporated into the outer layer of the core, the center of the
core would be formed by compression molding a core material to form
a sphere with a diameter less than that of the finished core. The
outer layer of the core which incorporates the compressible
material is then either injection molded or compression molded
around the center of the core. Finally, the cover would be
injection molded or compression molded around the core by
conventional means.
While it is apparent that the invention disclosed herein is well
calculated to fulfill the objects stated above, it will be
appreciated that numerous modifications and embodiments may be
devised by those skilled in the art. Therefore, it is intended that
the appended claims cover all such modifications and embodiments as
falling within the true spirit and scope of the present
invention.
* * * * *